Air shutter and installation method thereof

ABSTRACT

An insect/dust-proof air shutter which can positively prevent intrusion of foreign mater such as insects and dust and further trap intruded insects is provided. The air shutter  1  has side casings  2, 3  between which a passage space S is formed through which an inside space of a room is communicated to an outside space, the side casing  2  has an air suction openings  21  and an air discharge opening  22  proximate horizontally to one another and opening toward the passage space S, the side casing  3  has an air suction opening  31  and an air discharge opening  32  proximate horizontally to one another and opening toward the passage space S, the suction openings  21, 31  face the discharge openings  32, 31  respectively across the passage space S, air passages  23, 24  are formed in each of the side casings  2, 3 , air sucked through each of the suction openings  21, 31  is reversed in flow direction horizontally by 180° in each of the air passages  23, 24  to be blown out from each of the discharge openings  22, 32 , and air streams blown out from the discharge openings and sucked through the suction openings form circulating air streams flowing laterally across the passage space thereby forming double air films covering the passage space S.

TECHNICAL FIELD

The present invention relates to an air shutter installed at a doorway where temperature differential exists between outside and inside thereof to interrupt outside air from flowing into a room and cold air inside the room from flowing out, particularly an insect-proof/dust-proof air shutter installed at a doorway of a sanitarily controlled room such as in a food factory, which can effectively prevent intrusion of foreign matter such as dust, particularly can catch intruded insects.

BACKGROUND ART

An air curtain for preventing intrusion of outside air through the doorway of a thermal insulation door of a building is known from Japanese Patent Publication No. 37-12183. According to the invention, air spouts from both right and left sides horizontally to interrupt infiltration of outside air and exfiltration of inside air through the doorway. However, as the two airflows collide to each other in the central region of the doorway opening, the amount of airflow is larger as compared with a case of an air curtain formed by an air stream spouting only from one side, resulting in increased power consumption.

As one of means to prevent intrusion of foreign matter such as insects, dust, etc. through the doorway opening of a sanitarily controlled space in a food factory and so on, a system of forming an air curtain to cover the doorway as an air wall was proposed and has been put to practical use. There are known as systems of forming an air curtain such as a downward spouting system in which air is spouted from the top of the opening downward, a vertical circulation system in which air is spouted from the top of the opening downward and sucked into the pit provided on the floor to be returned to the top of the opening through an air duct, a lateral flow system in which air is spouted horizontally from a lateral side of the opening toward the other lateral side thereof, a lateral circulation system in which air is spouted horizontally from a lateral side of the opening toward the other lateral side thereof where the air is sucked in to be returned through an air duct to the lateral side from which the air was spouted, a lateral countercurrent circulation system in which air is spouted horizontally from both of lateral sides of the opening toward the other lateral sides of the opening respectively where the air is sucked in to be returned to the lateral sides where the air was spouted respectively, a lateral countercurrent system in which air is spouted horizontally from both lateral sides of the opening toward the central zone of the doorway opening leaning toward outside of the opening, etc.

For example, in Japanese Patent No. 2920759 (patent literature 1) is disclosed an air curtain producing system of lateral countercurrent type. In the system, air discharge openings are provided at each of the side walls facing each other across the doorway opening such that air is spouted horizontally from each of the discharge openings leaning with a proper angle respectively toward outside of the doorway so that two air streams spouting from each of the discharge openings collide against each other with a certain crossing angle and join together in the range of the doorway opening, wherein the air streams are different in velocity such that the one is relatively high and the other is relatively low, thereby suppressing occurrence of turbulence at the confluence of both the air streams, occurrence of eddies due to pulsation of air stream, and occurrence of infiltration of outside air and intrusion of insects rising on the infiltration air.

In Japanese Laid-Open Patent Application No. 2006-57928 (patent literature 2) is disclosed an air shutter unit, in which an entrance space is formed at the doorway of a room by both side walls, a ceiling part, and a floor part, and the entrance space is intercepted by an air curtain or curtains formed by air streams flowing laterally across the entrance space, wherein two air curtains are formed by two air streams flowing laterally across the entrance space in two separate planes in opposite directions to each other, each of the air stream circulating from the one to the other air stream. With this air shutter unit, the air streams are allowed to circulate in separate planes so that the air streams do not collide with each other and occurrence of turbulence in the doorway opening is prevented as much as possible, with the result that the effect of preventing intrusion of insects is increased.

DISCLOSURE OF THE INVENTION Problem to be Solved

It is supposed that the lateral countercurrent system and lateral countercurrent circulation system are superior in foreign matter interrupting effect among systems mentioned above.

However, there are problems as follows:

In the lateral countercurrent circulation system, an air shutter of portal construction provided with fans therein is installed at the doorway, air is spouted from the right and left side so that air streams collide with each other at the central zone of the doorway opening, and the rebounded air stream is sucked into the right and left gatepost of the portal construction to be circulated. However, it is difficult to suck in the air streams rebounded from the central part because of small suction opening area, and the air streams disturb air near the doorway openings, intrusion of insects tends to occur.

In the lateral countercurrent system, an air shutter of portal construction provided with fans therein is installed at the doorway, air is spouted from the right and left side so that air streams collide with each other at the central zone of the doorway opening, and air to be spouted is sucked through the suction openings of the gateposts, each of the suction openings being provided on a face different from the face on which each of the discharge opening is provided. In this case, also the air streams disturb air near the openings, and intrusion of insects tends to occur.

In the system disclosed in the patent literature 1, air is spouted horizontally from discharge openings at velocities different to each other leaning with a proper angle respectively toward outside of the doorway so that two air streams spouting from each of the discharge openings collide against each other with a certain crossing angle and join together in the range of the doorway opening, and air to be spouted is sucked through the suction openings of the gateposts, each of the suction openings being provided on a face different from the face on which each of the discharge opening is provided.

However, actually it is difficult to bring the air stream of lower velocity into integration with the air stream of higher velocity, turbulence occurs at the confluence region, and intrusion of insects tends to occur.

In the system disclosed in the patent literature 2, air stream is circulated laterally across the doorway opening without colliding with each other, so turbulence does not occur, however, further improvement in effect of preventing insect intrusion is demanded. Particularly, to positively remove insects intruded when the air shutter is operated is not taught in any of prior arts, and it has been demanded to provide an air shutter capable of interrupting foreign matter and positively removing intruded insects.

The present invention aims in light of the problems of the prior art to provide an insect/dust-proof air shutter capable of preventing intrusion of foreign matter such as insects and dust credibly and further capable of catching intruded insects.

Means to Solve the Problem

To solve the problems, the present invention proposes an air shutter, especially suitable for use as an insect/dust-proof air shutter, for producing an air stream or streams flowing laterally across a passage space through which an inside space of a room is communicated to an outside space in order to intercept the inside space of the room from the outside space, in which two air streams flowing in two planes in the passage space laterally crossing the passage space in opposite directions to one another are formed, and the air streams reverse their flow directions horizontally by 180° at each of both side end wall parts of the passage space so that the air streams circulate from one to the other air stream, thereby forming double air films crossing laterally in the passage space.

Further, the invention proposes an air shutter, especially suitable for use as an insect/dust-proof air shutter, for producing an air stream or streams flowing laterally across a passage space through which an inside space of a room is communicated to an outside space in order to intercept the inside space of the room from the outside space, in which a discharge opening and a suction opening are provided horizontally proximate to one another at each of side end wall parts forming the passage space such that the suction opening of one of the side end wall parts faces the discharge opening of the other side end wall part across the passage space, and an air passage is provided in each of the side end wall parts such that air sucked in through each of the suction openings is reversed in its flow direction horizontally by 180° to be blown out from each of the discharge openings, thereby the air streams circulate from one to the other air stream with each of the air streams flowing in opposite direction to one another, thereby forming double air films crossing laterally in the passage space.

According to the invention, double air films are formed separately in the depth direction of the passage space, so air streams forming the air films do not interfere with each other and turbulence does not occur, and the function of interrupting intrusion of foreign matter can be stably maintained. Further, as the double air films are formed by air streams flowing in directions opposite to one another, even if one of the air films is broken by personnel or things passing through the passage space, the inside space can be intercepted from the outside space reliably. Further, as the air streams are reversed in flow direction by 180° horizontally in each of the side casings, a large area of air passage for introducing the sucked air stream to the fans provided in the side casings can be secured in each of the side casings, pressure loss in the suction side of the fans is reduced, and uniform distribution of velocity of blowing out air stream in vertical direction is attained.

Further, the air shutter is applied particularly suitably for the purpose of interrupting intrusion of insect by providing an insect net in the air passage of each of the side casings. By this, insects blown about by the air stream and sucked in through the suction openings can be positively trapped by the insect nets just behind the suction openings. Further, by providing the insect net, it can be prevented that insects sucked in the casing are crashed and scattered in the casing.

The invention proposes an air shutter, especially suitable for use as an insect/dust-proof air shutter, for producing an air stream or streams flowing laterally across a passage space through which an inside space of a room is communicated to an outside space in order to intercept the inside space of the room from the outside space, in which a discharge opening and a suction opening are provided vertically proximate to one another at each of side end wall parts forming the passage space such that the suction opening of one of the side end wall parts faces the discharge opening of the other side end wall part across the passage space, and an air passage is provided in each of the side end wall parts such that air sucked in through each of the suction openings is reversed in its flow direction vertically by 180° to be blown out from each of the discharge openings, thereby the air streams circulate from one to the other air stream with each of the air streams flowing in opposite direction to one another, and thus a single air film consisting of two air streams flowing in opposite direction to one another is formed crossing laterally in the passage space, and in which an insect net is provided in said air passage.

According the invention, air streams are formed in one plane in the passage space in the upper and lower region with each air stream flowing in directions opposite to one another to circulate from one to the other air stream. The air streams do not interfere with each other and do not disturb each other, and the inner space of the storage can be stably intercepted from the outside space. As the suction opening and discharge opening are vertically juxtaposed in each side casing, the apparatus can be small sized. Further, insects can be positively trapped by the insect net provided in the air passage of each of the side casings.

It is preferable that a damper which is opened when air shutter is operated and closed when the air shutter is not operated is provided at the suction opening. By providing such a damper at the suction opening of each of the side casings, intruded insects can be prevented from escaping through the suction opening when operation of the air shutter is stopped, that is, when the air streams are not formed.

Further, it is preferable that the insect net contains an insecticide. By this, trapped insects can be killed and removed without permitting the intruded insects from escaping through the suction openings.

It is preferable to provide an insect catching means in the air passage of each of the side casings. By providing the insect catching means and positively catching insects intruded from the suction opening, intruded insects can be caught without fail.

The insect catching means may be an insect catching sheet having adhesion property. By this, intruded insects can be caught credibly preventing them from escaping through the suction openings.

The insect catching means may have an insect luring lamp that emits rays to which insects are attracted. By luring insects by the insect luring lamp, effect of catching insect can be increased.

ADVANTAGES OF THE INVENTION

As has been described heretofore, according to the present invention, as double air films are formed separately in the depth direction in the passage space, air streams forming the air films do not interfere with and disturb each other, and function of interrupting intrusion of foreign matter can be stably maintained. Further, as the double air films are formed by air streams flowing in directions opposite to one another, even if one of the air films is broken by personnel or things passing through the passage space, the inside space can be reliably intercepted from the outside space.

According to other embodiment of the present invention, air streams are formed in one plane in the passage space in the upper and lower region with each air stream flowing in directions opposite to one another to circulate from one to the other air stream. The air streams do not interfere with each other and do not disturb each other, and the inner space of the storage can be stably intercepted from the outside space. As the suction opening and discharge opening are vertically juxtaposed in each of the side wall parts, the apparatus can be small sized.

Further, by providing insect net in the air passage of each of the side wall parts, insects blown about by air streams sucked through the suction openings can be trapped by the insect nets just behind the suction opening.

By providing a damper at the suction opening of each of the side wall parts, intruded insects are prevented from escaping through the suction openings even when the operation of the apparatus is stopped, that is, when air streams are not formed.

Furthermore, by providing an insect catching means in the air passage of each of the side wall parts, insects can be positively caught and insect rejection efficiency can be increased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of the first embodiment of the insect/dust-proof air shutter according to the present invention.

FIG. 2 a is a schematic sectional lateral view of the insect/dust-proof air shutter of FIG. 1, and FIG. 2 b is a sectional view along line X-X in FIG. 1 a.

FIG. 3 is a plan view of the insect/dust-proof air shutter of FIG. 1.

FIG. 4 is a schematic perspective view of the second embodiment of the insect/dust-proof air shutter according to the present invention.

FIG. 5 is a schematic sectional lateral view of the insect/dust-proof air shutter of FIG. 2.

FIG. 6 is a plan view of the insect/dust-proof air shutter of FIG. 2.

FIG. 7 a and FIG. 7 b represent an example of configuration of the damper in the present invention when fans are operated and when the fans are not operated.

FIG. 8 a, FIG. 8 b, and FIG. 8 c are drawings for explaining the insect catching means in the present invention when an insect net is provided, when an insect net coated with medical substance is provided, and when insect catching sheets and insect luring lamps are provided respectively.

FIG. 9 is a schematic perspective view of the relevant part of the insect/dust-proof air shutter of the invention provided with an insect takeoff opening.

FIG. 10 is a graph showing insect rejection efficiency in the first embodiment.

FIG. 11 is a graph showing insect rejection efficiency in the second embodiment.

FIG. 12 is a drawing showing an example of positioning of the insect/dust-proof air shutter.

FIG. 13 is a schematic perspective view of the third embodiment of the insect/dust-proof air shutter according to the present invention.

FIG. 14 a is a longitudinal sectional view of installed state of the insect/dust-proof air shutter of the third embodiment showing when goods are carried into or out of the storage room from or to a truck in the good disposing room between the storage room and outside space with the overhang door (vertically sliding door) is opened, and FIG. 14 b is a section along line C-C in FIG. 14 a.

FIG. 15 is a graph showing the change of temperature in the storage room with time when the air curtain of FIG. 13 is formed and not formed.

FIG. 16 a is an illustration showing distribution in vertical direction of air velocity passing through the doorway in the lateral central region of the doorway opening when temperature differential exists between outside and inside thereof, and FIG. 16 b is an illustration showing the velocity distribution with velocity vectors.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present invention will now be detailed with reference to the accompanying drawings. It is intended, however, that unless particularly specified, dimensions, materials, relative positions and so forth of the constituent parts in the embodiments shall be interpreted as illustrative only not as limitative of the scope of the present invention.

FIGS. 1 to 3 depict the insect/dust-proof air shutter of the first embodiment of the invention, FIGS. 4 to 6 depict the insect/dust-proof air shutter of the second embodiment of the invention, FIGS. 7 a and b depict the configuration of the damper, FIGS. 8 a, b, and c are drawings for explaining the insect catching means, FIG. 9 is a schematic perspective view of the relevant part of the insect/dust-proof air shutter of the invention provided with an insect takeoff opening, FIGS. 10 and 11 are graphs showing insect rejection efficiency in the first and second embodiment respectively, and FIG. 12 is a drawing showing an example of positioning of the insect/dust-proof air shutter.

As shown in FIG. 12, an air shutter 1 of the invention is an apparatus installed at the entrance of a storage space 10 which is needed to be sanitarily controlled. It prevents foreign matter such as insects, dust, etc. from intruding into the storage space 10 and traps the insects intruding thereinto.

The first embodiment of the air shutter is very high in preventing intrusion of insects and suitable to maintain the enclosed storage space very sanitarily. The second embodiment is a simplified type of insect/dust-proof air shutter which is also capable of preventing foreign matter from intruding the storage space.

THE FIRST EMBODIMENT

The first embodiment of the insect/dust-proof air shutter will be explained with reference to FIGS. 1 to 3.

An air shutter 1 is installed at the entrance of a storage space 10. A passage space S is provided between the storage space 10 and the space 11 outside the storage space. The passage space S is formed by a ceiling part 12, a floor part 13, a left side wall part and a right side wall part.

The air shutter 1 has a left side casing 2 and a right side casing 3 located at opposite positions across the passage space S respectively. The left side casing 2 is located at the left side wall part side and the right side casing 3 is located at the right side wall part side.

The left side casing 2 is partitioned partly in two in the depth direction of the passage space S, and has a suction opening 21 and a discharge opening 22 both opening toward the passage space S. An air passage 23 is formed by the partial partition in the left side casing 2 to allow the suction opening 21 to be communicated to the discharge opening 22 so that a circulation air stream A is reversed in flow direction by 180° horizontally as shown in FIG. 3 by C in an air flow reversing part of the air passage 23 and spouted from the discharge opening 22 as a circulation air stream B. The air passage 23 may be shaped to have corners in horizontal section as shown in FIG. 3 or the corners are rounded to form a half circle. Further, the left side casing may be of a rectangular column or circular column.

The right side casing 3 is configured similar to the left side casing 2, and has a suction opening 31, a discharge opening 32, and an air passage 33 for allowing the openings to be communicated to each other, the air passage 33 having an air flow reversing part.

The suction opening 21 of the left side casing 2 faces the discharge opening of the right side casing 3 and the discharge opening 22 of the left side casing 2 faces the suction opening 31 of the right side casing 3 respectively across the passage space S.

In the air passages 23, 33 are located a plurality of fans 24, 34 respectively arranged vertically.

In this embodiment, fans 24, 34 are provided at the discharge openings 22, 32 as an example. It is preferable that the fans 24, 34 are arranged vertically at equal spacing, by which discharge velocity of air becomes even.

With the configuration, the circulation air stream A sucked in through the suction opening 21 of the left side casing 2 is reversed in flow direction in the air passage 23 as indicated by a circulation air stream C, pressurized by the fan 24 to be discharged from the discharge opening 22 to form a circulation air stream B. The circulation air stream B is sucked in through the suction opening 31 of the right side casing 3, reversed in flow direction as indicated by a circulation air stream D, pressurized by the fan 34 to be discharged from the discharge opening 32 to form a circulation air stream A.

Usually, air velocity necessary to interrupt intrusion of an insect (medium to small in size such as a fly) is about 3˜4 m/s. Therefore, it is preferable in the apparatus that air stream velocity at the lateral central part of the passage space S is about 3˜4 m/s or larger, preferably 4 m/s or larger. By composing to form double layers of air film, the range of defense against intrusion of foreign matter of each of the air curtains formed by air stream spouting from left and right side casings can be halved. For example, when the width of the air passage S is 2200 mm, it is allowable that the air stream from one of the casings keeps velocity of 4 m/s or larger only in the range from the discharge opening to the lateral center of the passage space S, that is, in the range of 1100 mm from the discharge opening. In this case, velocity of air at the discharge opening must be 8 m/s or larger.

According to the first embodiment, two air curtains are formed separately in depth direction of the passage space S, i.e. in the direction perpendicular to lateral direction. Therefore, air streams forming the two air curtains do not interfere with each other and the air streams do not disturb each other. As the two air streams flow in counter direction to each other, even if one of the air streams is interrupted by a person or substance passing the passage space, the air streams are not fully broken, and the inside space of the room can be intercepted steadily from the outside space.

Further, as the circulation stream is reversed horizontally by 180° in flow direction in each of the casings, a large section area can be secured for the air flowing from the suction opening to the discharge opening resulting in decreased flow resistance in the suction side, and also discharge air velocity can be evened along vertical direction of the discharge opening.

Further, it is preferable, as shown in FIG. 7, to provide a damper 5 to each of the suction openings 21, 22 of the insect/dust-proof air shutter 1. The damper 5 is located nearer than an insect net 4 mentioned later to the suction opening 21. The damper 5 opens when the air shutter is operated and closes when the air shutter is not operated.

The damper 5 may be composed such that it opens/closes automatically by the pressure of the air stream or driven to open/close by an electric motor.

Trapped insects can not escape toward outside the apparatus from the suction opening by virtue of flowing air during operation of the apparatus. However, when the operation of the apparatus is stopped, the trapped insects may be able to escape toward outside the apparatus from the suction opening because there is no air flow. By providing a damper at each of the suction opening and closing the damper when not operating the apparatus, the trapped insects can be prevented from escaping from the suction opening.

Further, as shown in FIG. 8 a, an insect net 4 is provided in the air passage 23 in the suction opening 21 side. The insect net 4 covers all over the air passage 23 in the suction opening side and the mesh size of the insect net is determined in accordance with the size of insect intending to trap.

It is further preferable that a part of the air passage 23 between the insect net 4 and the damper is defined as an insect trapping space 25, and provide an insect catching means there. The insect catching means is a means to trap insects intruded into the insect trapping space 25 in a positive manner.

FIG. 8 b shows a construction in which a net 4′ coated with medical substance is provided as an insect net. The net 4′ is an insecticide containing net on or in which medical substance having insecticidal effect is coated or borne.

FIG. 8 c shows a construction in which insect catching sheets 8 having adhesion property is provided on the side walls of the insect trapping space 25 and insect luring lamps 7 that emit rays to which insects are attracted. By irradiating the insect catching sheets 8 by the insect luring lamps 7, insects gather near the insect catching sheets 8 to be caught thereby.

It is suitable that the side casing 2 is provided with an insect takeoff opening 6 as shown in FIG. 9. Insects bumped the insect net 4 and fallen to the bottom, and insect catching sheets 8 to which insects are adhered, can be taken out through the insect takeoff opening 6. It is recommendable that operation of the air shutter is stopped when taking out insects through the insect takeoff opening 6.

With the construction, insects blown about by the air stream are sucked in through the suction openings 21, 31, and these insects can be trapped by the insect net 4 positively. The insect net 4 prevents the insects sucked into the apparatus from being crashed and scattered by the fans 24, 34.

Further, by providing insect catching means such as an insect luring lamp 7 and insect catching sheets 8 in order to positively trap insects, rejection of insects can be done in a convincing way.

In FIGS. 7 to 9, internal construction of the left side casing 2 was explained, it is similar as to the right side casing 3.

THE SECOND EMBODIMENT

The second embodiment of the insect/dust-proof air shutter will be explained with reference to FIGS. 4 to 6. Detailed explanation will be omitted as to construction the same to the first embodiment.

An air shutter 1 is installed at the entrance of a storage space 10. The air shutter 1 has a left side casing 2 and a right side casing 3 located at opposite positions across the passage space S respectively.

In the second embodiment, the left side casing 2 is partitioned partly vertically in two, and has a suction opening 21 and a discharge opening 22 both opening toward the passage space S. An air passage 23 is formed by the partial partition in the left side casing 2 to allow the suction opening 21 to be communicated to the discharge opening 22 so that a circulation air stream A is reversed in flow direction by 180° vertically in an air flow reversing part of the air passage 23 and spouted from the discharge opening 22 as a circulation air stream B.

The right side casing 3 is configured similar to the left side casing 2, and has a suction opening 31, a discharge opening 32, and an air passage 33 for allowing the openings to be communicated to each other, the air passage 33 having an air flow reversing part.

The suction opening 21 of the left side casing 2 faces the discharge opening of the right side casing 3 and the discharge opening 22 of the left side casing 2 faces the suction opening 31 of the right side casing 3 respectively across the passage space S.

In the air passage 23, 33 are located a plurality of fans 24, 34 respectively arranged vertically. In the embodiment, fans 24 are provided at the discharge openings 22 that are provided in the lower half of the left side casing 2, and fans 34 are provided at the discharge openings 32 that are provided in the upper half of the left side casing 3, as an example.

With the configuration, the circulation air stream A sucked in through the suction opening 21 provided in the upper half of the left side casing 2 is reversed in flow direction in the air passage 23 as indicated by a circulation air stream C, pressurized by the fans 24 to be discharged from the discharge opening 22 provided in the lower half of the left side casing 2 to form a circulation air stream B. The circulation air stream B is sucked in through the suction opening 31 provided in the lower half of the right side casing 3, reversed in flow direction as indicated by a circulation air stream D, pressurized by the fan 34 to be discharged from the discharge opening 32 provided in the upper half of the right side casing 3 to form a circulation air stream A.

According to the second embodiment, a single layer of air film is formed in the passage space S by the circulation air stream A and B with each air stream flowing in directions opposite to each other. The air streams do not interfere with each other and do not disturb each other, and the inner space of the storage can be intercepted from the outside space. Further, as the suction opening and discharge opening are vertically juxtaposed, the apparatus can be small sized.

Furthermore, the circulation stream is reversed horizontally by 180° in flow direction in each of the casings, so a large section area can be secured for the air flowing from the suction opening to the discharge opening resulting in decreased flow resistance in the suction side, and also discharge air velocity can be evened along vertical direction of the discharge opening.

It is preferable also in the second embodiment that the damper 5, insect catching means, and insect takeoff opening 6 shown in FIGS. 7 to 9 are provided similarly as is in the first embodiment.

[Insect Trapping Test]

Insect trapping test was carried out using insect/dust-proof air shutters of the first and second embodiment to verify the effect of insect rejection.

A test was carried out with the first embodiment in two cases the width of the doorway opening is 2700 mm and 2200 mm (see FIG. 12). An air shutter 1 provided with insect nets 4 were used. The air shutter 1 is operated at various frequencies of AC power inputted to the motors for driving the fans, and a certain number (40) of domestic flies were inputted from a throwing-in opening 16 provided in the outside space 11. Then the door 15 was opened for 30 minutes. After 30 minutes elapsed, the door 15 was shut, and an insecticide was sprayed. Then the number of flies in the outside space 11 and that in the storage space 10 were counted.

Rejection efficiency was calculated from the following formula (1).

η=(xoff−xon)/xoff×100  (1)

where η is rejection efficiency [%], ‘x’ is intrusion rate [%], ‘off’ indicates when operation of the air shutter is stopped, and ‘on’ indicates when the air shutter is operated.

Intrusion rate ‘x’ was calculated from the following formula (2).

x=nf/ns×100  (2)

where ‘x’ is intrusion rate [%], ‘ns’ is the number of domestic flies inputted, and ‘nf’ is the number of domestic flies that had intruded into the storage space 10 during the door 15 had been opened for 30 minutes.

The result of the test is shown in FIG. 10. It is recognized from the test result that rejection efficiency higher than 70% can be obtained by using the air shutter of the first embodiment, and that, by increasing the velocity of the air stream by increasing frequencies of AC power inputted to the motors for driving the fans, rejection efficiency higher than 90% can be obtained in the case of doorway width of 2200 mm and rejection efficiency higher than 85% in the case of doorway width of 2700 mm.

Thus, it was verified that extremely high insect trapping effect can be attained by using the air shutter of the first embodiment and forming circulation air stream of velocity higher than a certain value.

About half of the domestic flies inputted were trapped by the insect nets 4 and insect trapping effect of the insect nets 4 was confirmed.

A similar test was carried out using an air shutter of the second embodiment, and the test result is shown in FIG. 11. The test was carried out when doorway width is 1000 mm and 2200 mm.

It is recognized from test result that rejection efficiency higher than 70% can be obtained when the width of doorway opening is 1000 mm.

However, rejection efficiency decreases when the width of doorway opening is 2200 mm, so air shutter construction should be selected in accordance with the width of doorway opening.

The construction of the first embodiment is effective when the width of doorway opening is wide, and the construction of the second embodiment is effective when the width of doorway opening is not so wide.

THE THIRD EMBODIMENT

FIG. 13 is a schematic perspective view of the third embodiment of the present invention. FIG. 14 a is a longitudinal sectional view of installed state of the insect/dust-proof air shutter of the third embodiment showing when goods are carried into or out of the storage room from or to a truck in the good disposing room between the storage room and outside space with the overhang door (vertically sliding door) is opened, and FIG. 14 b is a section along line C-C in FIG. 14 a. FIG. 15 a graph showing the change of temperature in the storage room with time when the air curtain of FIG. 13 is formed and not formed. FIG. 16 a is an illustration showing distribution in vertical direction of air velocity passing through the doorway in the lateral central zone of the doorway opening when temperature differential exists between outside and inside thereof, and FIG. 16 b is an illustration showing the velocity distribution with velocity vectors.

As shown in FIG. 13, the air shutter of the third embodiment of the invention is a portal construction composed of a gatepost 112 for producing a cold exfiltration air interrupting air stream, a gatepost 113 for producing warm infiltration air interrupting air stream and located to face the gatepost 112 across the doorway opening, and an upper girder 116.

A lower slit nozzle 112 a is provided in the lower part of the doorway side face of the gatepost 112, the lower end of the slit nozzle 112 a reaches the floor 114. Above the lower slit nozzle 112 a is provided a suction opening 112 b extending upward until it reaches the upper girder 116. Inside the gatepost 112 are located lower side fans 112 c and the inside is formed into a suction duct 112 d which guides the circulation air 111 sucked in through the suction opening 112 b to the suction side of the lower side fans 112 c.

On the other hand, an upper slit nozzle 113 a is provided in the upper part of the doorway side face of the gatepost 113, the upper end of the slit nozzle 113 a reaches the upper girder 116. Below the upper slit 113 a is provided a suction opening 113 b extending downward until it reaches the floor 114. Inside the gatepost 113 are located upper side fans 113 c and the inside is formed into a suction duct 113 d which guides the circulation air 111 sucked in through the suction opening 113 b to the suction side of the upper side fans 113 c.

The upper girder 116 bridges the gatepost 112 and 113 at the top thereof. The upper girder 116 prevent warm air tending to pass through the warm infiltration air interrupting air stream from overriding the warm infiltration air interrupting air stream to infiltrate into the cold storage room, thus infiltration of warm air from the upper part of the doorway opening is perfectly prevented.

The height of the lower slit nozzle 112 a of the gatepost 112 is about 0.5H(H is the height of the gatepost), and air spouts from the lower slit nozzle 112 a at relatively lower velocity to form a cold exfiltration air interrupting air stream 110 a. The air stream 110 a spreads in vertical direction to a height of about 0.9H from the floor 114 at the suction opening 113 b of the gatepost 113 to be sucked in therethrough.

The height of the upper slit nozzle 113 a of the gatepost 113 is about 0.1H from the upper girder 16, and air spouts from the upper slit nozzle 113 a at relatively higher speed (because the area of the slit nozzle 113 a is smaller than that of the slit nozzle 112 a) to form a warm infiltration air interrupting air stream 110 b. The air stream 110 b spreads in vertical direction to a height of about 0.4H from the upper girder 116 at the suction opening 112 b of the gatepost 112 to be sucked in therethrough.

Thus, the high speed air stream spouted from the slit nozzle 113 a of the gatepost 113 forms the warm infiltration air interrupting air stream 110 b in the warm air infiltration interrupting zone in the upper region of the doorway opening, and the low speed air stream spouted from the slit nozzle 112 a of the gatepost 112 forms the cold exfiltration air interrupting air stream 110 a in the cold air exfiltration interrupting zone in the lower region of the doorway opening.

The high speed air stream is sucked in through the suction opening 112 b of the gatepost 112 for producing cold exfiltration air interrupting air stream and introduced via the suction duct 112 d to the lower side fans 112 c to be spouted from the lower slit nozzle 112 a as the low speed air stream to form the cold exfiltration air interrupting air stream 110 a in the cold air exfiltration interrupting zone.

The low speed air stream is sucked in through the suction opening 113 b of the gatepost 113 for producing warm infiltration air interrupting air stream and introduced via the suction duct 113 d to the upper side fans 113 c to be spouted from the upper slit nozzle 113 a as the high speed air stream to form the warm infiltration air interrupting air stream 110 b in the warm air infiltration interrupting zone.

Referring to FIGS. 14 a and 14 b, the cold storage room 130 a is partitioned by an overhang door (vertical sliding door) 112 from the good disposal room 131 which is provided between the door 121 and outside space 130 b. The air shutter of the invention which is a portal construction composed of a gatepost 112 for producing a cold exfiltration air interrupting air stream, a gatepost 113 for producing warm infiltration air interrupting air stream, and an upper girder 116, is installed in front of the overhang door 121. The drawings show the state a truck 126 is advanced into the disposal room 131 provided with a pent roof, a curtain 122, and shelters 124; a double-leaf hinged door 126 a of the truck 126 is opened, and the overhang door 121 is slid up to open the doorway between the cold storage room 130 a and disposal room 131. The overhang door 121 is opened after the truck is advanced into the disposal room, then the air shutter is operated, and the cold exfiltration air interrupting air stream 110 a and the warm infiltration air interrupting air stream 110 b are formed.

The gateposts 112 and 113, and the upper girder 116 are surrounded with a panel 123 so that the periphery of the portal construction is hermetically sealed against the storage room 130 a.

With the air shutter of the third embodiment, it is enough that the portal construction is installed in front of the doorway of the cold storage room with the periphery thereof sealed hermetically against the cold storage room, so that the air shutter can be applied to any kind of doorway opening. Therefore, an air shutter of low cost and enhanced maintainability can be provided.

FIG. 15 is a graph showing the change of temperature in the storage room with time when the air curtain of FIG. 13 is formed and not formed. As can be recognized from the graph, the change of room temperature of −24° C. after 4 minutes was as follows:

When the air curtain was formed; temperature rise was about 2° C.

When the air curtain was not formed; temperature rise was about 22° C.

Thus, with the air shutter, significant effect of interrupting air flow through the doorway opening was achieved by the air curtain.

The third embodiment is an air shutter to be installed in a doorway, temperature differential existing between spaces outside and outside of the doorway, wherein a warm air infiltration interrupting air stream and a cold air exfiltration interrupting air stream are formed respectively in a warm air infiltration zone in an upper region of the doorway opening and a cold air exfiltration zone in a lower region of the doorway opening sandwiching an intermediate windless region such that the air streams circulate from one to the other air stream, whereby warm air infiltration from the outside space in the upper region and cold air exfiltration from the inside space in the lower region are interrupted.

In FIGS. 16 a and 16 b is shown a result of measurement of velocity distribution of air passing through the doorway opening when the door is opened. As can be seen in the drawing, the velocity of air flowing out from the inside space through the opening area along the floor is the maximum. It decreases with increase in height from the floor and becomes zero at a height of about 0.8H, which means a windless region. It increases inversely from the height of 0.8H upward, that is, outside warm air infiltrates into the inside space, i.e. cold storage room.

It is recognized that a large part of the doorway opening is a cold air exfiltration zone and a small part in the upper region of the doorway opening is a warm air infiltration zone.

The embodiment is based on the measurement result, and a warm air infiltration zone is defined in the upper region of the doorway opening and a warm infiltration air interrupting air stream which is small in sectional area across its flow direction and high in flow velocity is formed in the warm air infiltration zone, a cold air exfiltration zone is defined in the lower region of the doorway opening and a cold exfiltration air interrupting air stream which is large in sectional area across its flow direction and low in flow velocity is formed in the cold air exfiltration zone, and a boundary zone of the two air streams is defined in the winless intermediate zone.

A circulating interruption air stream is formed by the warm infiltration air interrupting air stream and the cold exfiltration air interrupting air stream so that the outside and inside spaces of the doorway is intercepted by the circulation of the same air, thereby decreasing the temperature differential between the temperature of the inside space and that of the circulating interruption air stream, by which occurrence of haze and dew formation can be prevented.

It is preferable that the circulating interruption air stream consists of a cold exfiltration air interrupting air stream of large in flow sectional area and low in flow velocity spouted toward the doorway opening from the cold exfiltration air interrupting air stream producing part of one of the gateposts where a suction duct and lower side fans are provided, and a warm exfiltration air interrupting air stream of small in flow sectional area and high in flow velocity spouted toward the doorway opening from the warm infiltration air interrupting air stream producing part of the other gatepost where a suction duct and upper side fans are provided, the gateposts being located facing each other across the doorway space.

As the cold exfiltration air interrupting air stream producing part provided with fans and the warm infiltration air interrupting air stream producing part provided with fans are provided respectively in each of the gateposts with the suction ducts integrated in the gateposts respectively, it is not necessary to provide suction ducts and fans for blowing out the air sucked in through the ducts separately, compact, low cost, and maintenance-easy construction is realized.

It is preferable in the air shutter of the third embodiment that the warm infiltration air interrupting air stream zone covers a region extending by 0.1H to 0.4H from the top of the doorway opening and the cold exfiltration air interrupting air stream zone covers a region extending by 0.5H to 0.9H from the bottom of the doorway opening. This is determined based on the test result shown in FIGS. 16 a and 16 b. As explained before, FIG. 16A shows distribution of velocity of air flow passing through the doorway opening perpendicular thereto in the lateral center region thereof, and FIG. 16 b shows the velocity distribution with velocity vectors.

The velocity of air flowing out from the inside space through the opening area along the floor is the maximum. It decreases with increase in height from the floor and becomes zero at a height of about 0.8H, which means a windless region. It increases inversely from the height of 0.8H upward, that is, outside warm air infiltrates into the inside space, i.e. cold storage room. The warm air infiltration zone is limited to a small region in the upper part of the doorway opening.

Therefore, in the embodiment, the warm air infiltration zone is defined in the region extending by 0.1H to 0.4H from the top of the doorway opening, the cold air exfiltration zone is defined in the region extending by 0.5H to 0.9H from the top of the doorway opening, the warm infiltration air interrupting air stream is formed in the warm air infiltration zone, the cold exfiltration air interrupting air stream is formed in the cold air exfiltration zone, and a boundary zone of the two air streams is defined in the windless intermediate zone.

The warm infiltration air interrupting air stream is preferably directed to the outside of the doorway opening by an angle of 0˜20° and the cold exfiltration air interrupting air stream is preferably directed to the inside of the doorway opening by an angle of 0˜20°.

Further, it is suitable that the warm infiltration air interrupting air stream producing part and cold exfiltration air interrupting air stream producing part are provided in a pair of heat insulating doors provided at the doorway opening.

It is preferable that an upper girdle is provided to bridge the gateposts and the air shutter is formed into a portal construction. By this, infiltration of warm air into storage room along the ceiling of the doorway can be prevented.

It is also preferable that a short curtain member is provided in front of the warm infiltration air interrupting zone in the upper region of the doorway opening to interrupt heat flow between the outside and inside space of the doorway opening. By this, heat insulation effect is further increased by the curtain member provided in the upper region of the doorway in addition of the heat insulation effect due to the decreased temperature differential between the temperature of the circulation air and that of the storage room caused by allowing the same air to circulate through the warm infiltration air interrupting air stream and cold exfiltration air interrupting air stream.

Since the short curtain member is provided only in front of the warm infiltration air interrupting air stream zone in the upper region of the doorway opening and it does not shield the middle and lower region of the doorway opening, the short curtain member does not obstruct viewing the inside of the cold storage room, does not disturb entering and leaving of a service vehicle such as a forklift truck, and does not harm operation efficiency of cargo handling.

INDUSTRIAL APPLICABILITY

The air shutter according to the invention can prevent intrusion of foreign matter such as insects and dust into the inside space of a cold storage to sanitarily control the inside space and at the same time can prevent infiltration of outside air into the inside space and exfiltration of inside air to the outside space, so it can be applied suitably also for the purpose of maintaining temperature differential between the inside and outside spaces.

Further, according to the invention, by composing such that a plurality of fans and a suction air passage are provided inside each of the side casings or gateposts located at both sides of the doorway, ample suction air passage area can be easily secured and increase in negative suction pressure which is caused when suction air passage area is small can be suppressed. Therefore, decrease in velocity and flow rate of the interrupting air stream due to increased negative suction pressure can be prevented, in other words, power to drive the fans to produce the interrupting air stream of required velocity and flow rate can be decreased.

Further, since the short curtain is provided only in front of the warm infiltration air interrupting air stream zone and it does not shield the middle and lower part of the doorway opening, deterioration in visibility due to providing the curtain can be evaded. 

1. An air shutter for producing an air stream or streams flowing laterally across a passage space through which an inside space of a room is communicated to an outside space in order to intercept the inside space of the room from the outside space, wherein two air streams flowing in two planes in the passage space laterally crossing the passage space in opposite directions to one another are formed, and the air streams reverse their flow directions horizontally by 180° at each of both side end parts of the passage space so that the air streams circulate from one to the other air stream, thereby forming double air films crossing laterally in the passage space.
 2. An air shutter for producing an air stream or streams flowing laterally across a passage space through which an inside space of a room is communicated to an outside space in order to intercept the inside space of the room from the outside space, wherein a discharge opening and a suction opening are provided horizontally proximate to one another at each of side end wall parts forming the passage space such that the suction opening of one of the side end wall parts faces the discharge opening of the other side end wall part across the passage space, and an air passage is provided in each of the side end wall parts such that air sucked in through each of the suction openings is reversed in its flow direction horizontally by 180° to be blown out from each of the discharge openings, whereby the air streams circulate from one to the other air stream with each of the air streams flowing in opposite direction to one another, thereby forming double air films crossing laterally in the passage space.
 3. An air shutter according to claim 2, wherein an insect net is provided in said air passage.
 4. An air shutter for producing an air stream or streams flowing laterally across a passage space through which an inside space of a room is communicated to an outside space in order to intercept the inside space of the room from the outside space, wherein a discharge opening and a suction opening are provided vertically proximate to one another at each of side end wall parts forming the passage space such that the suction opening of one of the side end wall parts faces the discharge opening of the other side end wall part across the passage space, and an air passage is provided in each of the side end wall parts such that air sucked in through each of the suction openings is reversed in its flow direction vertically by 180° to be blown out from each of the discharge openings, whereby the air streams circulate from one to the other air stream with each of the air streams flowing in opposite direction to one another, and thus a single air film consisting of air two air streams flowing in opposite direction to one another is formed crossing laterally in the passage space, and wherein an insect net is provided in said air passage.
 5. An air shutter according to claim 1, wherein a damper which is opened when the air shutter is operated and closed when the air shutter is not operated is provided at the suction opening.
 6. An air shutter according to claim 3, wherein said insect net contains an insecticide.
 7. An air shutter according to of claim 1, wherein an insect catching means is provided in said air passage.
 8. An air shutter according to claims 7, wherein said insect catching means is an insect catching sheet having adhesion property.
 9. An air shutter according to claim 7, wherein said insect catching means is an insect luring lamp that emits rays by which insects are attracted.
 10. An air shutter according to claim 1, wherein a circulating interruption air stream is consisted of a warm air infiltration interrupting air stream and a cold air exfiltration interrupting air stream formed respectively in a warm air infiltration zone in an upper region of the doorway opening and in a cold air exfiltration zone in a lower region of the doorway opening sandwiching an intermediate windless region such that the air streams circulate from one to the other air stream.
 11. An air shutter according to claim 10, wherein the circulating interruption air stream consists of a cold exfiltration air interrupting air stream of large in flow sectional area and low in flow velocity spouted toward the doorway opening from the cold exfiltration air interrupting air stream producing part of one of the gateposts where a suction duct and lower side fans are provided, and a warm exfiltration air interrupting air stream of small in flow sectional area and high in flow velocity spouted toward the doorway opening from the warm infiltration air interrupting air stream producing part of the other gatepost where a suction duct and upper side fans are provided, the gateposts being located facing each other across the doorway space.
 12. An air shutter according to claim 2, wherein a damper which is opened when the air shutter is operated and closed when the air shutter is not operated is provided at the suction opening.
 13. An air shutter according to claim 4, wherein said insect net contains an insecticide.
 15. An air shutter according to claim 2, wherein an insect catching means is provided in said air passage.
 16. An air shutter according to claim 4, wherein an insect catching means is provided in said air passage.
 17. An air shutter according to claims 15, wherein said insect catching means is an insect catching sheet having adhesion property.
 18. An air shutter according to claims 16, wherein said insect catching means is an insect catching sheet having adhesion property.
 19. An air shutter according to claim 17, wherein said insect catching means is an insect luring lamp that emits rays by which insects are attracted.
 20. An air shutter according to claim 18, wherein said insect catching means is an insect luring lamp that emits rays by which insects are attracted. 